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Better tooling, faster.

Better tooling, faster

How D&F Corp uses PC-based CAD/CAM to generate NC cutter paths and checking data for CMMs.

D&F Corp, a tooling company based in Sterling Heights, MI, wants to do jobs for the auto and aerospace industries faster and at lower cost than anyone else in the business. Two years ago, however, the company found certain jobs were not being done competitively.

"We were using a machine-specific CAM system in conjunction with our milling machines to generate NC cutter paths," recalls Van Smith, vice-president and general manager. "This approach was satisfactory for plane surfaces, but as soon as we got involved with common contoured surfaces, the system was much too slow. Furthermore, we could not perform surface or line extensions for our checking fixtures.

"For example, when we check the tolerances of an automobile door panel, that part must be held by a checking fixture. It must have rails around its periphery to match the extended surface of the door panel. Our old system couldn't be used to check these surfaces. And finally, we wanted to get into computer-aided product design, but our old CAM system didn't have the capability."

Besides having to contend with a lack of speed and versatility in their old CAM system, D&F faced stiffer competition brought about by an industry trend toward decentralizing operations. "The Big Three automakers no longer wish to retain sole responsibility for tool engineering," notes Smith. "Therefore, they are contracting a great deal of work to outside vendors.

"That outflow of work from the automakers has stimulated stiff competition among numerous subcontractors. They receive design information, and design master die models for parts. Then they build the body gages and fixtures to check the accuracy of these dies."

Shopped the field

To gain speed and flexibility in programming, D&F installed three Solution 3000 PC-based CAD/CAM systems from Micro Engineering Solutions Inc, Novi, MI. During the past two years, these systems have proved so successful in filling the company's needs, that D&F has installed additional systems.

Surprisingly, the Solution 3000s were recommended by several of D&F's competitors. "We looked at three or four different systems, ranging in price from $200,000 down to $20,000 apiece," says Frank Trapani, electronic data leader and CAD/CAM operator. "We were almost at the point of buying another brand of system, when contacts in our business told us about Solution 3000.

"We tried it, and as far as I was concerned, it was a better system at less than half the price. I could then put two programmers to work instead of one, at about the same cost."

Two of D&F's Solution 3000 systems are used to create cutter paths, while the third aids in developing checking data. After sending five operators to a training session at Micro Engineering Solutions, D&F immediately put their CAD/CAM systems and operators to work.

About 90 percent of D&F's projects are for customers in the auto industry. These projects consist of designing and making master die models, body gauges, and fixtures, along with a small amount of product design. Most of the remaining 10 percent of the company's tooling projects are for the aircraft and aerospace industry.

In most cases, tool design data come to D&F on magnetic tape, in wireframe or surface form, and are loaded directly into CAD/CAM. In other cases, files arrive by telephone line and modem. Data on mylar or blueprint drawings are digitized into 3-D graphics files.

Regardless of a graphics file's format--IGES, DES, or other--Solution 3000 automatically translates data into a form that enables an operator to design shapes, check fixtures, or create cutter paths. Currently some 80 percent of the company's jobs involve either generating cutter paths or developing checking data for use on CMMs.

Download on disks

Operators of the company's CNC milling machines receive NC programs on floppy disks, each of which may contain several programs. Along with the disks, operators are given printed plots of part geometry and cutter paths, plus printed program lists for the disks.

"These lists show the sequences of programs, and where each program starts and stops," Smith explains. "Normally a single milling machine is used to run all programs on a disk, but cutting-tool changes are made between program segments.

"For example, the first program on a disk may be employed to cut flat surface sections with a 1.25"-dia cutter. The second program may cut the periphery of the part with a 0.75"-dia cutter, and a third program may cut small air-flow bars with a 0.125"-dia cutter.

"To produce a fender model completely, for instance, we'd probably use six or seven programs. Our new CAD/CAM systems generate these NC programs in half the time needed by our old CAM system."

To check a job, a CAD/CAM operator calls up a 3-D image of a model on the screen. He rotates the image, observes different planes and angles, and determines where points must be checked. He then keys this information into the system, and transfers the output disk to one of the company's four CMMs.

"We merely tell the computer how closely we want the paths measured, and it sets them up," Smith explains. "In many cases, the customer instructs us concerning locations at which they want tooling checked. The new CAD/CAM systems generate checking data in about one-fourth the time needed by our old system. In design applications, with a qualified operator, we could probably reduce CAD times to one-fifth those needed on the old system."

Smith adds that D&F's new CAD/CAM systems are providing other capabilities not available to the company from their old system. "For example, flat-bottom cutting is something we wanted to do for a long time, but couldn't because the old system--and other new systems we looked at--used ball-nosed cutting.

"Now we can cut with a circular, flat-bottomed tool. The CAD/CAM system automatically compensates for its diameter to ensure that a vertical surface is not violated. We no longer need to depend on the mill operator to tell the machine control computer how far back to keep the cutter.

"If our operator missed by a millimeter, we'd be cutting into a wall by a millimeter. With Solution 3000, all you need do is tell the system the diameter of the cutter you want to use. The control computer takes it from there.

"To get that capability in another CAD/CAM system, we would've had to pay from $175,000 to $200,000--about 10 times the cost of a Solution 3000 system. This system's Millmaster module is one of the major reasons we opted for Solution 3000."

After this computer system has become firmly entrenched in the company's CAM operations, D&F plans to increase CAD applications. "To get our feet wet, we're designing some brackets," reports Frank Trapani. "Soon we'll extend our efforts into binder design." 2101

PHOTO : Observed by Van Smith, two CAD/CAM operators generate NC cutter paths and measurement

PHOTO : checking data on D&F's new Solution 3000 systems. The company is gradually expanding its

PHOTO : activities in CAD.

PHOTO : Vice-president and general manager Van Smith inspects the operation of a Bridgeport CNC

PHOTO : milling machine that is cutting a model. "Our new CAD/CAM systems allow flat-bottom

PHOTO : cutting and violation checking," he says. "In addition, a software module called

PHOTO : Millmaster enables the computer to automatically compensate for cutter diameter. This

PHOTO : ensures that we don't violate vertical surfaces."
COPYRIGHT 1989 Nelson Publishing
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Copyright 1989 Gale, Cengage Learning. All rights reserved.

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Title Annotation:micro-computer based system for numerically control parts milling
Publication:Tooling & Production
Date:Oct 1, 1989
Previous Article:Drilling micro-size deep holes.
Next Article:Tracking tool-coating payback.

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